A refrigerant distributor is needed at an inlet of a heat exchanger configured to operate as a condenser or an evaporator of a refrigeration cycle device, in order to separate the refrigerant into multiple paths when such a heat exchanger has a divided, multiple refrigerant paths inside. The refrigeration cycle device may be an air-conditioning apparatus, or a refrigerating device.
Air-Conditioning Apparatus.
Further, for example, for a multi-type air-conditioning apparatus in which a plurality of outdoor units and/or indoor units are connected in parallel, a refrigerant distributor is needed for distributing refrigerant to each of the units from a main refrigerant passage.
When a heat transfer tube of the heat exchanger is made of aluminum, an aluminum material processed by shaving or other processing is used for a member of a distributing section of the refrigerant distributor. Further, outflow pipes and an inflow pipe connected to the distributing section are also each configured by using an aluminum material. To join the outflow pipes with the distributing section and to join the inflow pipe with the distributing section, a joining process involving a brazing process is commonly used due to complicated shapes of these joined members. To perform the brazing process, an aluminum brazing material configured with an alloy of aluminum and silicon is used as a brazing material. Further, the members are joined together by alloying the aluminum brazing material with the outflow pipes, the distributing section, and the inflow pipe each by performing a heating process with the use of a burner or other devices. Accordingly, the outflow pipes, the refrigerant distributor, the inflow pipe, and the brazed parts are all structured with either aluminum metal or an aluminum alloy.
The refrigerant distributor, the heat exchanger, and the air-conditioning apparatus configured by using aluminum metal are installed in an outdoor environment and are therefore prone to have chloride ions adhered to the surface thereof, the chloride ions being derived from sea salt grains transported in the outside air. The adhesion of the chloride ions locally destructs an aluminum oxide film being formed on the surface of the aluminum and having corrosion resistance. A local corrosion is thus developed starting with the destruction location. When the local corrosion keeps being developed, a through hole may be formed, as a result, through which the refrigerant can leak. Consequently, the devices may reach the end of the product life earlier than expected.
To inhibit the development of the local corrosion, a method is effective that forms a “sacrifice positive electrode layer” being a material that is electrochemically less noble (more unstable) than aluminum on the surface of the aluminum metal, so that the sacrifice positive electrode layer is corroded first preferentially. To form such a sacrifice positive electrode layer (material) for aluminum, an aluminum-zinc alloy obtained by mixing zinc with aluminum is commonly used. Generally-known examples of an aluminum material having a sacrifice positive electrode layer formed thereon obtained by forming such a sacrifice positive electrode layer on the surface of aluminum include “a zinc-sprayed aluminum material”, and “an aluminum clad material having a sacrifice positive electrode layer formed thereon”, among others. The zinc-sprayed aluminum material is obtained by forming an aluminum-zinc alloy by spraying melted metal zinc onto the surface and subsequently performing a heating process to cause the metal zinc on the surface to diffuse to the inside (see Patent Literature 1, for example). The aluminum clad material having a sacrifice positive electrode layer formed thereon is obtained by putting an aluminum-zinc alloy material together with an aluminum material and further performing a rolling and pressure-welding process thereon at high temperature.